Curiosity got the better of me so I decided to install Snow Leopard on clean external USB drive (this is a rather slow drive, I believe it is only 4500 RPM), but good enough to test things out.

I formatted the drive before installation in Leopard (HFS+ Journaled, GUID partition), booted off the install DVD and proceeded to install on this external disk. Installation took about 50 min (this is not upgrade but clean install).

After the install was finished, I manually copied over some applications from my Leopard install (together with their application settings and preferences files in Library and
Library). All of them functioned properly.

The color profile for my 30' ACD screen looked a little too bright and less contrasty (this is gamma 2.2 profile I created for Leopard some time ago), but it is rendered differently in Snow Leopard. Which brings me to another point. My ancient Monaco Optix XR screen calibration software (with USB spectrometer) works with Snow Leopard as well. It does require Rosetta though.

Next thing I tried booting in 64 bit kernel. That worked fine, but now I wanted to add my printers. HP LaserJet 1300 was recognized instantly and added for me, so I guess Apple already provides 64 bit driver for it.

Next is the Epson Stylus Photo R2880. It was recognized (as in type and model) but no driver was available for it. However, Epson has just recently released the driver for it. The question was is it 64 bit as well. As it turns out the installer for the drive requires Rosetta, which wasn't very encouraging, but once installed the driver works just fine with 64 bit kernel. So I guess they do provide 64 bit driver as well.

As you can see the overall system performance has degraded quite a bit. Snow Leopard performance is only about 82% of Leopard performance.

Close inspection shows that some things are actually faster in Snow Leopard, e.g. CPU has higher score, Thread test has higher score, Memory test is faster. However, quartz test is slower, and Open GL test is 2 times slower.

This is quite a degradation in performance, and I'm hoping it will be addressed in GPU driver upgrades.

Also, I also noted the dreaded choppy animations, esp for dashboard, which is so choppy it is embarrassing. Like I said, this will probably go away with better driver.